A polymer electrolytic fuel cell (hereinafter referred to as PEFC) is a device which generates power and heat simultaneously by allowing a fuel gas containing hydrogen and an oxidant gas such as air containing oxygen to electrochemically react with each other.
In general, the PEFC is configured by laminating cells. A single cell is formed by sandwiching a film electrode assembly by using a pair of plate-shaped conductive separators, more specifically, an anode separator and a cathode separator. The film electrode assembly is provided with a main body portion of the film electrode assembly and a frame member that extends along the peripheral edge portion of the main body portion of the film electrode assembly to be placed thereon, in such a manner as to surround the main body portion of the film electrode assembly. The main body of the film electrode assembly is constituted by a polymer electrolyte film and a pair of electrode layers formed on the two surfaces thereof. Thus, a fuel gas and an oxidant gas are allowed to contact the two surfaces of the electrode layers to cause an electrochemical reaction. On the other hand, the frame member has a gasket, and the gap between the gasket and the separators is sealed, so that the fuel gas and the oxidant gas are prevented or restrained from leaking outside.
For example, the fuel cells having this structure are disclosed in Japanese Unexamined Patent Publication No. 2001-155745 and Japanese Patent No. 3368907. The fuel cell disclosed in Japanese Unexamined Patent Publication No. 2001-155745 relates to a gasket that is molded so as to cover the end face of a main body portion of a film electrode assembly and seal the end face. However, with this gasket, time-consuming tasks are required to place a sealing material that is made in close contact with the peripheral edge portion of the electrode layer just enough and evenly, with the result that this method is not suitable for mass production. Moreover, since the end face of the electrode layer of the main body portion of the film electrode assembly is covered with the gasket, the end face portion covered with the gasket fails to contribute to power generation, resulting in degradation in efficiency.
For this reason, by placing the gasket such that it does not cover the end portion of the electrode of the main body portion of the film electrode assembly, the entire face of the electrode layer can be used for power generation with this gasket. Japanese Patent No. 3368907 discloses a film electrode assembly shown in FIG. 3 thereof, which is provided with a gap between the electrode layer and the gasket (gas sealing member).